1. Field of the Invention
This invention relates to a semiconductor integrated circuit that incorporates a non-volatile memory.
2. Description of the Related Art
There has been known a semiconductor integrated circuit (a microcomputer, for example) that incorporates a non-volatile memory as a data memory or a program memory. A mask ROM (Read-Only Memory), a UV (ultraviolet ray) erasable EPROM (Electrically Programmable ROM) and a flash memory that is electrically programmable and erasable are known as examples of the non-volatile memory.
In recent years, there has been developed a semiconductor integrated circuit that incorporates a small capacity non-volatile memory in order to store data such as trimming data of an internal circuit incorporated in the semiconductor integrated circuit or an identification code of the semiconductor integrated circuit.
Information on a semiconductor integrated circuit that incorporates a flash memory may be found in Japanese Patent Application Publication Nos. 2000-112755 and 2000-105758, for example.
When rewriting the data such as the trimming data of the internal circuit or the identification code stored in the small capacity non-volatile memory incorporated in the semiconductor integrated circuit is required, it is necessary to use an electrically rewritable memory (a flash memory, for example) as the non-volatile memory.
However, using the flash memory increases the cost of the semiconductor integrated circuit, albeit only small capacity of non-volatile memory required for the purpose.
On the other hand, an electrically non-rewritable non-volatile memory, although less expensive, has a problem that the data once stored in the memory can be not updated and the non-volatile memory can be not reused.